This invention relates to a lubrication system for a machine and more particularly, to an improved lubrication system for a two-stroke internal combustion engine.
As is well-known, most mechanisms that employ moving parts require some form of lubrication. This is particularly true with machines which have variable volume defined by relatively movable components such as pumps or internal combustion engines. Some of these mechanisms include what might be considered to be closed lubricating systems wherein the lubricant is supplied to the moving parts and then is recirculated back to a supply tank for subsequent circulation. Other types of mechanisms, such as two-cycle engines, however, consume the lubricant during their operation.
For example, the traditional way in which two-cycle engines have been lubricated is to mix the fuel with the lubricant and introduce it to the crankcase chamber of the engine so that the components of the engine will be contacted by the fuel and lubricant and will thus be lubricated. However, it is also well-known that the amount of lubricant required does not vary necessarily in the same proportion as the amount of fuel required. In addition, there are disadvantages in requiring the operator to mix lubricant with the fuel.
There has been proposed, therefore, so-called direct lubricating systems for two-cycle engines wherein lubricant is supplied to the engine from a separate lubricating system. One place where the lubricant is introduced is to the sliding surface of the piston, normally through a port formed in the cylinder wall at a point below the bottom dead center position of the piston. There are, however, some disadvantages with this type of system under some circumstances.
Under many running conditions, the amount of lubricant which is required is quite small and with the type of system wherein the lubricant is supplied to the piston through an opening in the cylinder wall, the small amount of lubricant may not be able to flow sufficiently around the entire piston skirt. The use of multiple ports, although it offers one solution to this problem, is not completely satisfactory because of the small amounts of lubricant which may be required under certain running conditions.
In addition to these disadvantages, the supply of lubricant through a port in the cylinder wall can give rise to high lubricant concentrations at certain areas and this lubricant may break down under high temperatures and form deposits which can cause subsequent sticking of the piston.
It is, therefore, a principal object of this invention to provide an improved lubricating system for a machine.
It is a further object of this invention to provide an improved lubricating system for a two-cycle engine.
It is another object of the invention to provide an improved direct lubricating system for a two-cycle engine wherein the viscosity of the lubricant may be varied to suit varying running conditions.